2. The route to net zero GHG starts with electricity generation

Total UK electricity supply in 2018 was 334 TWh where 25 TWh was imported and 135 TWh came from non-GHG, with bioelect 36% (Drax), 16% nuclear plus 37% renewables, up nearly 10-fold over the previous decade, (64 TWh by wind turbines from 24 GigaWatts (GW) installed) (see Figure 3(b)). Some coal-fired power stations acted as supplier of the last resort. The 2020 UK government announcement to install an additional 40 GW of wind-power electricity by 2030 (to generate 110 TWh p.a.) roughly doubles current renewables output. However, that could not yet replace natural gas in generating electricity as a much larger supply of electricity will be needed to also power electric vehicles (EVs).

Renewable-energy sources like solar photovoltaics (PVs) and wind turbines have fallen rapidly in price and increased in efficiency over the past two decades. Relying purely on highly variable wind and sun sources requires constantly balancing electricity flow with short-run storage plus a larger backup storage system for windless nights and potentially long winter periods of still, cloudy weather. To sustain massively more power supply, substantial infrastructure and grid expansion are essential with improvements in its resilience facing more powerful storms and highly variable temperatures, as well as upgrading to an ‘intelligent system’.

Offshore wind turbines are easier to install than onshore given their 100 m-long blades, create marine reserves and fish sanctuaries when fixed and mix warm and cold layers improving supplies of nutrients and oxygen, when floating (see Dorrell et al., Reference Dorrell, Lloyd and Lincoln2022) following the successful Hywind Scotland trial. An ‘ocean battery’ on the seabed could hold water under pressure analogous to a hydro pump system and avoid shuttering off-shore wind turbines when there is excess output. As slowing wind speeds from smaller temperature differentials between the tropics and the poles (see Solaun & Cerdá, Reference Solaun and Cerdá2020) would reduce their benefits, waves and tides could also generate renewable energy. Geothermal energy could contribute beyond ground-source heat pumps. Additional non-GHG electricity generation methods include hydro (with pump and store and rivers), nuclear and small modular nuclear reactors (SMRs) building from the well-developed safe nuclear-powered engines in submarines. SMRs operate at lower temperatures so might be able to use the ‘spent’ uranium fuel rods from older reactors, helping reduce the problem of transuranic-waste disposal. Using electron-beam welding Sheffield ForgeMasters have reduced the vessel weld time from about a year to a day, greatly cutting costs. Although nuclear fusion has seen recent advances in superconducting magnets, increasing output efficiency, and reducing damage to tokamaks from helium, it seems unlikely to be a major energy contributor by 2050 (but see Greenwald, Reference Greenwald2020).

Natural gas (mainly methane, $ {\mathrm{CH}}_4 $ ) contributes about 40% of electricity output, with 140 megatons (Mt) p.a. $ {\mathrm{CO}}_2 $ emissions. Its replacement in electricity generation by non-GHG emitting methods seems feasible by 2050, even adding transport electrification and hydrogen production. The current government’s restricting solar farms and banning on-shore wind turbines, rather than crafting a location-specific positive framework, will not help, nevertheless a near zero target for natural gas in electricity generation seems possible without reducing employment or GDP growth, perhaps even increasing them with new opportunities. The benefits to the United Kingdom would certainly be greater if it developed a manufacturing and skills capacity for ‘green’ energy methods. Although replacing all 2200 TWh of energy purely by renewable electricity starting from the current 120 TWh might seem to require a 20-fold increase in non-GHG electricity—a compound growth rate of 10.5% p.a. over 30 years, even if increased demands from economic growth are offset by efficiency gains—much less is required as electricity is intrinsically more efficient in many uses such as replacing petrol-driven internal combustion engines, where heat losses are large, or heat pumps replacing gas boilers.

The recent large rises in UK electricity prices seen in Figure 3(c) despite extensive renewable supply (Panel (b)) suggest the pricing system is in urgent need of major reforms to remove dependence on the marginal producer (also see Grubb & Newbery, Reference Grubb and Newbery2018).

3. Prioritize electricity for decarbonizing transportation

Green electricity will be needed in all areas of our lives to achieve net zero, from housing to food to waste, but the priority should be the electrification of transportation as it will play a crucial symbiotic role in providing storage capacity. The demands on electricity capacity will be immense and so natural gas for electricity generation should continue to be used to ensure rapid electrification of the transport network, phasing out the use of natural gas as more green electricity comes on stream.

Distillates of oil are the main fuel for ground, air and sea transport. Taking these in turn, battery powered EVs are gradually replacing internal combustion engine cars. While cheaper over a lifetime, EVs are more expensive to purchase and have a relatively short journey capacity, yet take a non-negligible time to recharge, all of which discourages uptake. Improvements in batteries, standardised connectors, and increased production will help, as would increasing taxes on petrol and diesel as oil prices fall to maintain a constant high ‘pump price’.

Carbon nanotubes (CNTs, see, e.g., Sammed et al., Reference Sammed, Pan and Asif2020) are ‘rolled up’ sheets of graphene making electrode supercapacitors. These may be able to act as an electricity storage system to supply the battery driving an electric motor, with rapid charging and discharging. Graphene-based lithium-ion and solid-state batteries are also being developed following large cost reductions in graphene production.

When EVs become ubiquitous, supported by sufficient non-GHG electricity supply, having them plugged into the national grid when not in use would create a large electric backup system without additional investment beyond making the grid ‘intelligent’ to measure time of day flows of electricity to and from every vehicle (see Noel et al., Reference Noel, de Rubens, Kester and Sovacool2019). To encourage vehicle-to-grid (V2G) technology, a higher price could be paid for EV electricity supplied in peak periods. V2G would provide short-term storage to facilitate second by second balancing of electricity flows facing highly variable renewable supplies.

By not demonising road transport for its $ {\mathrm{CO}}_2 $ footprint and dangerous pollution, cars with internal combustion engines could be replaced at a rate matching their obsolescence, so employment can be maintained in vehicle manufacture and many of its ancillary industries rebased on EVs. A side benefit is eliminating the need for expensive catalytic converters, cutting vehicle production costs, eliminating a target for theft (which then exacerbates air pollution and GHGs, especially nitrous oxide) and reducing palladium mining. CNTs could help solve the UK’s rail system problem of a lack of electrification across much of the network by replacing diesel-electric trains, possibly also with hydrogen-driven trains. CNTs are lightweight, so might sustain economical electric-powered aircraft. Hydrogen fuel cells can power heavy vehicles like trucks and buses and offer long distances between charges: they would be almost GHG free if the hydrogen was also GHG free (see Section 4.1).

4. What individuals should do to decarbonise

Individuals should play their part in the move to net zero, supported by policies that include subsidies for investment in dwellings as the United Kingdom has some of the least energy-efficient housing stock in Europe.

Better house insulation is essential to reduce $ {\mathrm{CO}}_2 $ emissions from heating and cooling, which could include installing double or triple glazing, better loft insulation, draft reductions, foil between radiators and walls and so forth. Installing solar PVs panels and evacuated tube solar collectors on roofs and air and ground source heat pumps would reduce demands on GHG emitting energy sources, as would LED lighting. Fyfe et al. (Reference Fyfe, Grimes, Minehan and Taptiklis2022) show a benefit–cost ratio of more than four for jointly insulating New Zealand homes and installing heat pumps. Despite a higher proportion of apartment dwellings, France has installed several million heat pumps, so multiple occupancy buildings need not be a barrier, or entire villages. Housing accounts for around 30% of the UK’s $ {\mathrm{CO}}_2 $ emissions (roughly 150 million tonnes of $ {\mathrm{CO}}_2 $ ), much by heating from natural gas. Retrofitting a Glasgow tenement is a valuable pilot study highlighting what can be achieved.

5. Tackling agriculture’s carbon ‘footprint’

About 56% of the UK’s land area of 24 million hectares is farmed and 35% is ‘natural’ (see Rae, Reference Rae2017), leaving about 6% built on and about 3% ‘green urban’: rewilding will only marginally change these. Globally, agriculture has a large carbon ‘footprint’ of about a third of the anthropogenic GHG annual emissions (see Crippa et al., Reference Crippa, Solazzo and Guizzardi2021). Within the United Kingdom, agriculture emits 68% of all nitrous oxide (15 Mt CO ₂ Eq) and 47% of methane emissions (25 Mt CO ₂ Eq), which with $ {\mathrm{CO}}_2 $ emissions makes 46 Mt $ {\mathrm{CO}}_2 $ Eq p.a., slightly below the 1990 level of 53 Mt $ {\mathrm{CO}}_2 $ Eq; yet, the Government’s Environmental Land Management scheme makes no mention of GHGs or how to tackle them.

Nitrous oxide ( $ {\mathrm{N}}_2\mathrm{O} $ ) emissions come from nitrogen fertiliser use (see Tian et al., Reference Tian, Xu and Canadell2020) and globally have doubled in the last 50 years. UK fertiliser prices have tripled since 2020 so substitutes are urgently required both to lower food price inflation and reduce GHG emissions. Based on areas around volcanoes being fertile, ground-up basalt may be a useful fertilizer alternative and soil improver (see Allen, Reference Allen2024 (who records that agriculture started around the extinct volcano Karacadag in southern Anatolia where a large area of basalt supported einkorn wheat); Beerling et al., Reference Beerling, Kantzas and Lomas2020; Nunes et al., Reference Nunes, Kautzmann and Oliveira2014). Basalt also absorbs atmospheric CO ₂ so is doubly beneficial. Burying manure and slurry would reduce ammonia air pollution and improve soil as would pyrolysis of waste biomass to produce biochar, increasing crop yields and reducing GHG emissions (see Woolf et al., Reference Woolf, Amonette and Street-Perrott2010). Polyhalite, now being mined in the United Kingdom, is a hydrated sulphate of potassium, calcium and magnesium so is a natural fertilizer substitute.

Enteric methane emissions per annum per 100 animals, scaled by their weights, from livestock methanogenic bacteria are around 20 kg from dairy and 10 kg from beef cattle, 8–10 kg from sheep and goats and 5 kg from deer. Changes to farm mammal diets can reduce methane emissions (also saving energy so helping weight gain) such as adding dietary fumaric acid and small amounts of the seaweeds Asparagopsis armata or taxiformis (see Roque et al., Reference Roque, Salwen, Kinley and Kebreab2019; Kinley et al., Reference Kinley, Martinez-Fernandez and Matthews2020). As cattle inherit low methane production, selective breeding as well as changes to the mix of which species are bred for milk and cheese production would lower emissions. Changes to human diets are also possible, eating less mammal meat and more avian and plant nutrition. Steps to facilitate a shift to healthy diets include reordering menu items and preparing more enticing vegetarian or vegan dishes.

To economize on land, water, fertilizer and food waste, vertical and underground farms are benefitting from the reduced costs of LED lighting and can produce several crops per annum of some vegetables as well as breed fish of various kinds in hydroponic systems. Usually found in cities also saves energy from reduced transport and helps minimize extensions of farming into previously unused land, reducing species extinctions from loss of habitat. Protecting wetlands and peat would save GHG emissions.

Aquaculture is essential to the supply of seafood and seaweeds, but faces health concerns in many areas. More and larger marine reserves and saltwater fish sanctuaries (an incidental benefit of off-shore wind farms) with strong legal protection are needed, a step towards which is the High Seas Treaty aiming for 30% of the seas in protected areas.

6. Reducing GHGs from industry, chemicals and waste

Iron and steel industries are especially carbon intensive making high-heat based products from large and long-lived capital investments, but most forms of manufacturing require substantial energy inputs. However, reducing iron oxide by hydrogen rather than fossil fuels, as in HYBRIT, eliminates about 90% of steelmaking GHG emissions. Potential non-GHG high-heat solutions for manufacturing include electric arc and liquid hydrogen, but substantial new investment in these methods for mitigating large $ {\mathrm{CO}}_2 $ emissions is required.

Chemicals and plastics use fossil fuel inputs as well as needing energy, so reducing their GHG emissions entails more open and closed loop recycling where the former creates new but useful products from waste plastic. Reductions to artificial fertiliser use were noted above.

Less waste landfill would reduce methane leakage, and economic incentives can really help: the 5 pence charge per plastic bag in the United Kingdom from 2015 led to an 80% fall in their use, saving almost 13 billion after 2 years: similar charges to reduce other non-recyclable, often single use, items would be useful.

7. Summary and conclusions

Having been first into the Industrial Revolution, which has hugely enriched the world but accidentally created climate change, the United Kingdom should lead the world out. The United Kingdom has reduced its territorial $ {\mathrm{CO}}_2 $ emissions by 186 Mt from 554 Mt to 368 Mt (34%) so far this century, while per capita real GDP has risen by more than 25%, despite the ‘Great Recession’ (excluding pandemic and energy crisis-induced falls). The UK’s total ‘consumption-induced $ {\mathrm{CO}}_2 $ Eq’ emissions are higher than its territorial level through GHG embodied in net imports, although the large reductions achieved to date in electricity generation have a major domestic component. ‘Consumption-induced’ GHG will fall as the GHG emissions intensity of imports falls. Border tariffs on imports from high GHG or deforesting countries (adding to pressure to reduce environmental degradation and loss of habitat threatening species extinctions) could accelerate this (see Nordhaus, Reference Nordhaus2015, Reference Nordhaus2020).

To achieve net zero GHG emissions requires a joined up approach to decarbonizing to capture virtuous circles: solving some problems can help solve others. Sufficient non-GHG electricity generation is achievable with known technologies, but faces storage problems for periods when renewables do not generate power. Using EVs as storage units connected to the grid would facilitate short-term balancing of electricity flows. Conversely, once renewables capacity has greatly expanded, electrolysis and methane pyrolysis production of hydrogen would sustain 100% capacity renewables generation at ‘off-peak’, and via liquid hydrogen provide a potential high heat source for industry as well as medium-term storage as part of ‘power-to-X’ (hydro pump and store, batteries, flywheels, supercapacitors and ocean batteries on the seabed etc.). New buildings must be constructed with low GHG emissions and be net zero. Nitrous oxide, methane and other GHG emissions from food production can be reduced by replacing some nitrogen fertiliser by basalt dust, which also absorbs carbon dioxide and by biochar, and methane by dietary changes to ruminants. Human dietary changes are also feasible. These developments interact and would maintain employment and real per capita growth during the transition in both new industries and retrofitting transport and housing with upgrading of labour skills.

Carbon pricing (see Sterner et al., Reference Sterner2020) might facilitate GHG reductions where economical alternatives exist (although evidence of public opposition in some countries suggests limitations even when the revenue raised is rebated), as could cap and trade (successful for sulphur dioxide reductions implemented in the 1990 US Clean Air Act) where the EU Emissions Trading System has reduced GHGs.

Investments in non-GHG power generation including storage, infrastructure upgrades and EV charging points can be repaid via earnings on electricity sales. Natural obsolescence and scrapping of vehicles and domestic heating equipment anyway entails a replacement need, and economies of scale and efficiency improvements (Way et al., Reference Way, Ives, Mealy and Farmer2022) should see costs become increasingly favourable for doing so by EVs, heat pumps and domestic solar panels, but perhaps less so for SMRs and batteries. Retrofitting for better insulation will cut heating and cooling costs but will probably need to be subsidised, as will conversions of some industrial and chemical equipment to non-GHG power. Farming changes should reduce costs. Thus, although the gross investments over 25–30 years may total several £ trillions, similar sums would be needed to maintain the status quo of ‘business as usual’.

Castle and Hendry (Reference Castle and Hendry2020) find little evidence of aggregate costs from the UK’s GHG reductions to date, but workers in industries being replaced by technological change have usually bourn what should be social costs. Mitigating the inequality impacts on ‘stranded workers’ and regions from climate-related policies matters to maintain public support for a just transition to a ‘green economy’, not just warning about the risks to investors of ‘stranded assets’ in carbon intensive activities should future legislation suddenly impose zero GHG emissions after a serious deterioration in the climate. Political strategies to overcome climate policy obstructionism deserve consideration. Recovery from the pandemic and energy crisis does not preclude tackling burgeoning climate issues, building on hosting CoP26 in Glasgow despite its ineffectiveness globally: the United Kingdom could achieve a huge reduction in its GHG emissions if it adopted and maintained a coherent strategy. Indeed, if every country operated on a feasible, bespoke plan, many elements of what is a global problem could be solved.